The ignition system is an important part of the overall engine system and the distributor cap is an important device in the ignition system. Small part it may be but it plays a very important role in the working of an automobile. The distributor cap is a device in the ignition system that distributes electricity from the ignition coils to the spark plug wires at the right timing. It is usually made of hard plastic and a small amount of copper. Inside the distributor cap is the distributor rotor, which rotates as it receives current from the ignition coils and passes it on to the copper portion of the cap, which then passes it on to the spark plugs. The distributor cap is used to cover the distributor and its internal rotor. The distributor cap has one post for each cylinder and in the inside of the cap is a terminal that corresponds to each post and the plug terminals are arranged around the circumference of the cap according to the firing order in order to send the secondary voltage to the proper spark plug at the right time. It is a prime example of a component that will ultimately break down due to heat and vibration. Either the bakelite housing cracks or breaks or carbon deposit accumulation or erosion of its metal terminals can cause a distributor cap's failure. A contamination or a small crack in the distributor cap can cause the vehicle to stumble during its acceleration. Your Mazda distributor cap should be changed during tune-up or every two years. An easy way to check if you have a bad distributor cap is by checking if you can see sparking between the electrodes on the cap when the engine is running. Check our online store where we have a selection of Mazda distributor cap replacements you can choose from.